In a just-released promo for Tuesday's Britney Spears-themed episode of Glee, series stars Lea Michele and Heather Morris channel the singer's iconic styles from the past decade.
While Morris, who stars as ditzy cheerleader Brittany, takes center stage in the episode -- titled "Brittany/Britney" -- Michele offers up a rendition of "...Baby One More Time," wearing similar school girl duds that Spears wore in the music video. (Watch a preview above)
"She was so professional," Michele tells Access Hollywood of Spears, who filmed her cameo in August. "She looked incredible. She's so tiny!"
Michele says the singer was "great to work with. It was one of those things where you go to work and you're like, 'I can't believe we're doing this!'"
Though she confirms they shot a scene together, she says, "What we do together, I can't say. I will tell you it's incredibly iconic!"
Glee airs Tuesdays at 8 p.m./ET on Fox.